A safety ski binding usually has a toe clamp and a heel clamp adapted respectively to secure the toe and heel of a ski boot to the ski. At least one of these clamps is provided with a release mechanism that allows the respective part of the boot to pull free when it exerts a force exceeding a predetermined maximum level on the clamp. In this manner, in case of a fall or other skiing accident, the skiboot will pull free from the ski and injury to the skier will be minimized.
In a very popular and simple system the reslease clamp is provided with a generally cylindrical sleeve having an inwardly directed lip at its end toward the skiboot and an opposite closed end. A pressure pin has a broad cylindrical head received in the sleeve and a relatively thin shank extending from the sleeve and having an outer end adapted to fit within a corresponding recess either on the skiboot or on a sole plate carried thereon. A spring in the sleeve is braced at one end against the closed end of the sleeve and at the other end against the face of the cylindrical head of the pin so as to press this pin with a predetermined force against the skiboot or plate thereon. See for example German patent 2,254,268.
A disadvantage of such a system is that when enough pressure is exerted axially on the pin to displace it back against the spring, the pin then very readily tips within th sleeve so as to free the skiboot or skiboot plate. If a very stiff spring is provided to minimize this danger the binding is almost completely ineffective. Since as a rule the clamp should release both when the skiboot is tipped up and when it is slid longitudinally within the binding, this type of structure is very disadvantageous as once the ski has been slid longitudinally to a limited extent the boot can easily slip out of the binding.